package org.geogebra.common.util.opencsv;

/**
 Copyright 2005 Bytecode Pty Ltd.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

import java.util.ArrayList;
import java.util.List;

/**
 * A very simple CSV parser released under a commercial-friendly license. This
 * just implements splitting a single line into fields.
 *
 * @author Glen Smith
 * @author Rainer Pruy
 */
public class CSVParser {

	final char separator;

	final char quotechar;

	final char escape;

	final boolean strictQuotes;

	private String pending;
	private boolean inField = false;

	final boolean ignoreLeadingWhiteSpace;

	final boolean ignoreQuotations;

	/**
	 * The default separator to use if none is supplied to the constructor.
	 */
	public static final char DEFAULT_SEPARATOR = ',';

	public static final int INITIAL_READ_SIZE = 128;

	/**
	 * The default quote character to use if none is supplied to the
	 * constructor.
	 */
	public static final char DEFAULT_QUOTE_CHARACTER = '"';

	/**
	 * The default escape character to use if none is supplied to the
	 * constructor.
	 */
	public static final char DEFAULT_ESCAPE_CHARACTER = '\\';

	/**
	 * The default strict quote behavior to use if none is supplied to the
	 * constructor
	 */
	public static final boolean DEFAULT_STRICT_QUOTES = false;

	/**
	 * The default leading whitespace behavior to use if none is supplied to the
	 * constructor
	 */
	public static final boolean DEFAULT_IGNORE_LEADING_WHITESPACE = true;

	/**
	 * I.E. if the quote character is set to null then there is no quote
	 * character.
	 */
	public static final boolean DEFAULT_IGNORE_QUOTATIONS = false;

	/**
	 * This is the "null" character - if a value is set to this then it is
	 * ignored.
	 */
	static final char NULL_CHARACTER = '\0';

	/**
	 * Constructs CSVParser using a comma for the separator.
	 */
	public CSVParser() {
		this(DEFAULT_SEPARATOR, DEFAULT_QUOTE_CHARACTER,
				DEFAULT_ESCAPE_CHARACTER);
	}

	/**
	 * Constructs CSVParser with supplied separator.
	 *
	 * @param separator
	 *            the delimiter to use for separating entries.
	 */
	public CSVParser(char separator) {
		this(separator, DEFAULT_QUOTE_CHARACTER, DEFAULT_ESCAPE_CHARACTER);
	}

	/**
	 * Constructs CSVParser with supplied separator and quote char.
	 *
	 * @param separator
	 *            the delimiter to use for separating entries
	 * @param quotechar
	 *            the character to use for quoted elements
	 */
	public CSVParser(char separator, char quotechar) {
		this(separator, quotechar, DEFAULT_ESCAPE_CHARACTER);
	}

	/**
	 * Constructs CSVReader with supplied separator and quote char.
	 *
	 * @param separator
	 *            the delimiter to use for separating entries
	 * @param quotechar
	 *            the character to use for quoted elements
	 * @param escape
	 *            the character to use for escaping a separator or quote
	 */
	public CSVParser(char separator, char quotechar, char escape) {
		this(separator, quotechar, escape, DEFAULT_STRICT_QUOTES);
	}

	/**
	 * Constructs CSVParser with supplied separator and quote char. Allows
	 * setting the "strict quotes" flag
	 *
	 * @param separator
	 *            the delimiter to use for separating entries
	 * @param quotechar
	 *            the character to use for quoted elements
	 * @param escape
	 *            the character to use for escaping a separator or quote
	 * @param strictQuotes
	 *            if true, characters outside the quotes are ignored
	 */
	public CSVParser(char separator, char quotechar, char escape,
			boolean strictQuotes) {
		this(separator, quotechar, escape, strictQuotes,
				DEFAULT_IGNORE_LEADING_WHITESPACE);
	}

	/**
	 * Constructs CSVParser with supplied separator and quote char. Allows
	 * setting the "strict quotes" and "ignore leading whitespace" flags
	 *
	 * @param separator
	 *            the delimiter to use for separating entries
	 * @param quotechar
	 *            the character to use for quoted elements
	 * @param escape
	 *            the character to use for escaping a separator or quote
	 * @param strictQuotes
	 *            if true, characters outside the quotes are ignored
	 * @param ignoreLeadingWhiteSpace
	 *            if true, white space in front of a quote in a field is ignored
	 */
	public CSVParser(char separator, char quotechar, char escape,
			boolean strictQuotes, boolean ignoreLeadingWhiteSpace) {
		this(separator, quotechar, escape, strictQuotes,
				ignoreLeadingWhiteSpace, DEFAULT_IGNORE_QUOTATIONS);
	}

	/**
	 * Constructs CSVParser with supplied separator and quote char. Allows
	 * setting the "strict quotes" and "ignore leading whitespace" flags
	 *
	 * @param separator
	 *            the delimiter to use for separating entries
	 * @param quotechar
	 *            the character to use for quoted elements
	 * @param escape
	 *            the character to use for escaping a separator or quote
	 * @param strictQuotes
	 *            if true, characters outside the quotes are ignored
	 * @param ignoreLeadingWhiteSpace
	 *            if true, white space in front of a quote in a field is ignored
	 * @param ignoreQuotations whether to ignore quotes
	 */
	public CSVParser(char separator, char quotechar, char escape,
			boolean strictQuotes, boolean ignoreLeadingWhiteSpace,
			boolean ignoreQuotations) {
		if (anyCharactersAreTheSame(separator, quotechar, escape)) {
			throw new UnsupportedOperationException(
					"The separator, quote, and escape characters must be different!");
		}
		if (separator == NULL_CHARACTER) {
			throw new UnsupportedOperationException(
					"The separator character must be defined!");
		}
		this.separator = separator;
		this.quotechar = quotechar;
		this.escape = escape;
		this.strictQuotes = strictQuotes;
		this.ignoreLeadingWhiteSpace = ignoreLeadingWhiteSpace;
		this.ignoreQuotations = ignoreQuotations;
	}

	private static boolean anyCharactersAreTheSame(char separator,
			char quotechar,
			char escape) {
		return isSameCharacter(separator, quotechar)
				|| isSameCharacter(separator, escape)
				|| isSameCharacter(quotechar, escape);
	}

	private static boolean isSameCharacter(char c1, char c2) {
		return c1 != NULL_CHARACTER && c1 == c2;
	}

	/**
	 * @return true if something was left over from last call(s)
	 */
	public boolean isPending() {
		return pending != null;
	}

	public String[] parseLineMulti(String nextLine) throws CSVException {
		return parseLine(nextLine, true);
	}

	public String[] parseLine(String nextLine) throws CSVException {
		return parseLine(nextLine, false);
	}

	/**
	 * Parses an incoming String and returns an array of elements.
	 *
	 * @param nextLine
	 *            the string to parse
	 * @param multi
	 *            multiline
	 * @return the comma-tokenized list of elements, or null if nextLine is null
	 * @throws CSVException
	 *             if bad things happen during the read
	 */
	private String[] parseLine(String nextLine, boolean multi)
			throws CSVException {

		if (!multi && pending != null) {
			pending = null;
		}

		if (nextLine == null) {
			if (pending != null) {
				String s = pending;
				pending = null;
				return new String[] { s };
			}
			return null;
		}

		List<String> tokensOnThisLine = new ArrayList<>();
		StringBuilder sb = new StringBuilder(INITIAL_READ_SIZE);
		boolean inQuotes = false;
		if (pending != null) {
			sb.append(pending);
			pending = null;
			inQuotes = !this.ignoreQuotations;
		}
		for (int i = 0; i < nextLine.length(); i++) {

			char c = nextLine.charAt(i);
			if (c == this.escape) {
				if (isNextCharacterEscapable(nextLine,
						(inQuotes && !ignoreQuotations) || inField, i)) {
					sb.append(nextLine.charAt(i + 1));
					i++;
				}
			} else if (c == quotechar) {
				if (isNextCharacterEscapedQuote(nextLine,
						(inQuotes && !ignoreQuotations) || inField, i)) {
					sb.append(nextLine.charAt(i + 1));
					i++;
				} else {
					inQuotes = !inQuotes;

					// the tricky case of an embedded quote in the middle:
					// a,bc"d"ef,g
					if (!strictQuotes) {
						if (i > 2 // not on the beginning of the line
								&& nextLine.charAt(i - 1) != this.separator // not
																			// at
																			// the
																			// beginning
																			// of
																			// an
																			// escape
																			// sequence
								&& nextLine.length() > (i + 1)
								&& nextLine.charAt(i + 1) != this.separator // not
																			// at
																			// the
																			// end
																			// of
																			// an
																			// escape
																			// sequence
						) {

							if (ignoreLeadingWhiteSpace && sb.length() > 0
									&& isAllWhiteSpace(sb)) {
								sb = new StringBuilder(INITIAL_READ_SIZE); // discard
																			// white
																			// space
																			// leading
																			// up
																			// to
																			// quote
							} else {
								sb.append(c);
							}

						}
					}
				}
				inField = !inField;
			} else if (c == separator && !(inQuotes && !ignoreQuotations)) {
				tokensOnThisLine.add(sb.toString());
				sb = new StringBuilder(INITIAL_READ_SIZE); // start work on next
															// token
				inField = false;
			} else {
				if (!strictQuotes || (inQuotes && !ignoreQuotations)) {
					sb.append(c);
					inField = true;
				}
			}
		}
		// line is done - check status
		if (inQuotes && !ignoreQuotations) {
			if (multi) {
				// continuing a quoted section, re-append newline
				sb.append("\n");
				pending = sb.toString();
				sb = null; // this partial content is not to be added to field
							// list yet
			} else {
				throw new CSVException(
						"Un-terminated quoted field at end of CSV line");
			}
		}
		if (sb != null) {
			tokensOnThisLine.add(sb.toString());
		}
		return tokensOnThisLine.toArray(new String[tokensOnThisLine.size()]);

	}

	/**
	 * precondition: the current character is a quote or an escape
	 *
	 * @param nextLine
	 *            the current line
	 * @param inQuotes
	 *            true if the current context is quoted
	 * @param i
	 *            current index in line
	 * @return true if the following character is a quote
	 */
	private boolean isNextCharacterEscapedQuote(String nextLine,
			boolean inQuotes, int i) {
		return inQuotes // we are in quotes, therefore there can be escaped
						// quotes in here.
				&& nextLine.length() > (i + 1) // there is indeed another
												// character to check.
				&& nextLine.charAt(i + 1) == quotechar;
	}

	/**
	 * precondition: the current character is an escape
	 *
	 * @param nextLine
	 *            the current line
	 * @param inQuotes
	 *            true if the current context is quoted
	 * @param i
	 *            current index in line
	 * @return true if the following character is a quote
	 */
	protected boolean isNextCharacterEscapable(String nextLine,
			boolean inQuotes, int i) {
		return inQuotes // we are in quotes, therefore there can be escaped
						// quotes in here.
				&& nextLine.length() > (i + 1) // there is indeed another
												// character to check.
				&& (nextLine.charAt(i + 1) == quotechar
						|| nextLine.charAt(i + 1) == this.escape);
	}

	/**
	 * precondition: sb not empty
	 *
	 * @param sb
	 *            A sequence of characters to examine
	 * @return true if every character in the sequence is whitespace
	 */
	protected boolean isAllWhiteSpace(CharSequence sb) {
		boolean result = true;
		for (int i = 0; i < sb.length(); i++) {
			char c = sb.charAt(i);

			if (!Character.isWhitespace(c)) {
				return false;
			}
		}
		return result;
	}
}
